Plane Can Fly Inches Over Water
While browsing Google Earth last year, some users saw an interesting sight at a naval base on a Chinese shore: runways heading directly into the ocean. Some people who may have seen such a landscape before might have questioned whether China was developing similar technology to that built by the Soviets during the Cold War, and nearly forgotten since.
On Tuesday, scientists from Tongji University in Shanghai announced that they had indeed designed a new model of the famous but largely unknown "wing-in-ground" (WIG) plane, Reuters reported. The plane, which can carry up to 4 metric tons (nearly 9,000 pounds), flies just 18 inches over the surface of the water, yet manages speeds of up to 180 mph.
To achieve these numbers, WIG planes use a technique called "ground effect" to achieve a high lift/drag ratio. Wings traveling close to the water (or ground) feel an extra lift by a cushion of air compressed underneath them. This enables the planes to carry extremely heavy loads while using significantly less fuel--in the case of the Tongji plane, about half that of a similar vehicle.
The effect is not new, however. Even the Wright brothers, whose planes flew very low to the ground compared with today's models, took advantage of ground effect, though probably weren't aware of it. If you've ever noticed the speed a commercial plane feels to have just before it lands, that too is ground effect, caused by the air cushion trapped between the wings and the runway.
As I mentioned earlier, the Russians were the first to build WIGs, which they called "Ekranoplans" (or "screen planes"). Engineer Rostislav Evgenievich Alexeev of the Central Hydrofoil Design Bureau in Russia is credited as the lead designer of the 100-meter-long planes that could carry more than 1 million pounds at speeds of up to 250 mph.
It was the middle of the Cold War, however, and the Russians kept their invention secret. If anyone inquired about what these objects were, employees were instructed to say that they were floating stands for new high-speed boat engines. But the grandiosity and method of travel of these beasts inspired US spies at the time to refer to the strange forms as "Caspian Sea Monsters."
Although the Russians had plans to build 120 Orlyonok (or "Eaglet") Ekanoplan models, but ended up with just four in the late ‘70s. Although a good 80% of the size of a Boeing 747, the Orlyonok could fly for 2,000 km (1,200 miles) without landing. Sadly, one of these planes crashed and sunk, killing the entire crew. It still remains at the bottom of the sea. (But according to this review, it appears that you can still buy a 1:144 scale model of the plane.)
The challenges faced by the Russians in mainstreaming this technology were faced by many of their followers. Perhaps most importantly, the immense amount of power required for planes when attempting to take off or land in the water, due to the large waves the planes create, was a problem. Engineers also faced challenges in implementing reliable automatic control systems, protecting against corrosive sea water, and protecting the engine air intake against bird strikes.
Interestingly, in 2002, Boeing was looking into building a gigantic WIG plane called the "Pelican." The company's goals are astounding: the plane would be 300 feet long with a 500-foot wingspan, fly 10 times the speed of cargo planes, carry 1.5 million pounds, and cover 10,000 nautical miles on a tank of fuel. Besides these plans, however, the Pelican is still in the works.
As for the scientists at Tongji University, they plan to develop a 50-seat WIG by 2013, with 200 prototypes capable of carrying 200 to 400 metric tons scheduled for 2016 or 2017. Military, commercial and even space uses could be in the future for WIG technology.
More general info: the WIG page.
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